LBM studies at pore scale for graded anodic porous transport layer (PTL) of PEM water electrolyzer

Oxygen invasion inside graded porous transport layer (PTL) of titanium felt is investigated based on Shan-Chen Lattice Boltzmann Model. The computation domain is obtained from X-ray computed tomography. The pore-scale study aims to investigate the counter-current transport of fluids within the spatially distributed structure with application to polymer electrolyte membrane water electrolysis (PEMWE). The results indicate that the transport mechanism is gas fingering for a current density of 1.356 A cm −2 . The observed gas fingering is independent of the domain size, structure and boundary conditions in the studied ranges. But, the computed final local distribution of oxygen strongly depends on spatial porosity and pore size distributions. Furthermore, with different locations of the oxygen injection points along the invasion interface, different final saturation profiles are computed. The latter suggests the importance of oxygen entrance conditions, especially when the computational domain shall be realistically coupled with the catalyst layer along the oxygen invasion interface. • Shan-Chen LBM implemented for oxygen invasion in 3D reconstructed domains of commercially available titanium felt PTL. • Local variation of porosity and pore size distribution determined from X-ray tomography images. • Realistic invasion behaviour computed for various morphologies of the reconstructed PTL. • Dependency of local invasion behaviour on fiber alignment and local pore structure revealed. • Role of the boundary conditions at the oxygen inlet side highlighted.